Method of producing shaped articles from artificial or synthetic fiberor film-forming materials



Sept. 30, 1952 HOXlE 2,611,929 METHOD OF PRODUCING SHAPED ARTICLES FROMARTIFICIAL 9 0R SYNTHETIC FIBER OR FILM-FORMING MATERIALS Filed June 18,1951 INVENTOR. HOWARD M HOX/E ATTORN r.

' cipitant, or with a mixture of the Patented Sept. 30, 1952 METHOD OFPRODUCING SHAPED ARTICLES FROM ARTIFICIAL R SYNTHETIC FIBER- ORFILM-FORMING MATERIALS Howard M. Hoxie, Chester, Pa., assignor, by mesneassignments, to The Ohemstrand Corporation,

Decatur, Ala., a corporation of Delaware Application June 18, 1951,Serial No. 232,208

This invention relates to improvements in the production of synthetic orartificial fibers, films, or other shaped articles by the wet-spinningor wet-forming processes.

This application is a continuation-in-part of my application Serial No.125,679 filed November 5, 1949, issued as Patent Number 2,577,763, De-

cember 11, 1951.

I In wet-spinning or wet-forming, as conventionally practiced, asolution of the material to be shaped is extruded into a vesselcontaining a suitabl setting liquid which is continuously orperiodically withdrawn from the vessel, reconditioned, and returned tothe extrusion vessel.

I In making shaped articles from fiberor filmmethylformamide solution ofthe polymer into a setting bath consisting of water anddimethylformamide in controlled predetermined proportions, as disclosedin my pending application Serial No. 62,413, filed November 27, 1948.

I The present invention is concerned more particularly with wet-spinningor wet-forming proc esses in which a solution or dispersion of thefiberor film-forming material is extruded into a setting bath comprisingthe solvent and a precipitant in critical, controlled relativeproportions which must be maintained throughout the extrusion, and hasas one object to facilitate maintaining the relative proportion ofsolvent to precipitant in the setting bath substantially constant fromthe beginning to the end of the extrusion.

In accordance with the invention, a solution or dispersion of thefiberor film-forming materialis extruded into a setting bath comprisingthe predetermined proportion of solvent and precipitant to form theshaped article, the article is withdrawn from the bath and, prior to anydrying thereof, it is washed with the preprecipitant and a minorproportion of the solvent, and liquid from this initial washing of thearticle is continuously delivered to the setting bath. The

constituents of the liquid from the washing step 14 Claims. (01. 18-54)or to depend on periodic or stances including vinyl acetate, styrene,'j

. 2 i; are the same as the constituents of the setting bath, and bycorrelating the proportion of precipitant to solvent in the liquid fromthe wash-v ing and the rate of flow of such liquid'into'l the settingbath with the amount of solventiritroduced into the bath by the solutionof the material to be shaped, the composition of thebath may bemaintained constant. Thereforefwhen operating in accordance with theinvention, it is unnecessary to withdraw the setting'bath'irom thevessel in which the extrusion is performed,

hap-hazard additions of either solvent or precipitant to thegbath inorder to maintain the composition of the bath constant. The method ofthe invention can be, used for producing artificial or synthetic fibersor other shaped articles from any fiberorfilm forming material which canbedissolved 0r dispersed and wet-spun, when the shapinginvolves'precipitation only. Examples of suitable fiberand filmformingmaterials are the organic acid esters of cellulose, the-fiber-formingsynthetic resins: including polyamides, polyesters, fiber=forining vinylresins, polyvinyl alcohol, and fibeIrIQfming polymers of acrylonitrile.The solvent or dispersing agents selectedfwill depend on the particularfiberor film-forming material to be shaped. As examples of suitablesolvents or dispersing agents may be mentioned, acetone forcommerciaLsecondary, cellulose acetate and such fiber-forming vinylresins as those resulting from the. conjoint polymerization of vinylchloride and vinyl acetate or of vinyl "chloride and acrylonitrile andcontaining from' 40 to acrylonitrile in the molecule; hot-phenol 0rformamide ior polyamides; chloroform for the polyesters; anddimethylformamide, dirnethylacetamide or dimethylpropionamide foracrylonitrile polymers containing from '70 to 98% by weight ofacrylonitrile in the molecule and obtaiinedby polymerizing acrylonitrilewith one or moref'other monethylenically unsaturated polymerizablsubinyl chloride, vinyl monomers containing bas'i, tertiary nitrogensuch as the vinylp'yridi'nes and particularly the 2-vinylpyridines,5-vinyl"2- methylpyridine and the like, isobutene, "dimethylfumarate,methylmethacrylate, methacrylonitrile and acrylic acid and its esters.The solvent "and dispersing agents mentioned are illustrativejfonly andother solvents or dispersing agents maybe substituted for them. I Theprecipitant selected will depend on both 5o the'fiberor film-formingmaterial being shaped such material is dissolved or dispersed. It may beany liquid which is an extractive for the extrusion solvent ordispersing agent but inert to 4 fibers advance upwardly through thetrough 6, they are washed by liquid supplied to the trough from thevessel 9 with which the trough communicates, for example, with waterwhich may the fiber-.formingmaterial. ..When water meets 5 be heated toa temperature up to 100 C., for tnis essential requirement, water is thepreferred instance: from room temperature: to 100 C. precipitant for usein the setting bath and as The liquid precipitant for the washing, orthe the major component of the Washing liquid to .mixture of theprecipitant with a minor prowhich the fibers or the like are subjectedimme- "portion of solvent, is metered into vessel 9 diately after theirwithdrawal from th'e bath. 10". through pipe lil'provided with valve II,and A specific embodiment of theinvention 'convessels is provided with avertically adjustable templates the production of fibers or threads fromoverflow pipe [2. for adjusting the level of the solutions ordispersions ofacrylonitrile polymers ,liquid in vessel 9 to therebyadjust or control the containing, by weight in the polymer molecule, at.quantity of precipitant or of precipitant-solvent least 70% ofacrylonitrile, in dimethylacetamide, vmixture delivered to the trough.The liquid flows by spinning the solution into a setting mediumdownwardly through the trough countercurrently consisting of water and acontrolled proportion to-the'direction of the fibers and is collected inof dimethylacetamide. In a preferred embodithe vessel l3 supportedadjacent to vessel 2 conment, a solution of the acrylonitrile polymer in'taining the setting bath. A controlled portion of.....dimethylacetamide is continuously extruded into that liquid, whichalways comprises a mixture .asetting bath comprising a mixture of waterand of the precipitant and the solvent, is continujdiniethyla'cetamide.containing the dimethylously delivered to-vessel 2 through'pipe" 14 pro-Uacetamide in a selected. proportion. between 20 vided with valve I5,the rate of flow be ng conand' 70 by .volume, and the composition of thetrolled and correlated with the proportion of solsetting-bath ismaintained'constant by'washing vent in the bath so that the liquidintroduced the fibers as they are withdrawn from the bath from vesselI3'serves to compensate for the p ewith water onwater :containing aminor propor- 'cipitant and'solvent carried from the bath by the ii tionof dimethylace'tamide, and delivering the fr hly f rmed fi r n hi W y, hr l tive 1 liquid fromthe washing step into the setting proportions ofthe precipitant and solvent in the bath at acontrolled rate. I .Theconditions are setting'bath' are maintained substantially con- .selectedso that the composition of the setting Stantb'ath-does notvary more than2% from the pre- V ss l 2 is provid dwith an overflow p p 6;.-.determined volumetric proportions and the proformaintainingthe levelof the setting bath conportion of dimethylacetamide present in' thestantpand avertically adjustable overflow pipe setting bath is at least20% by volume. H associated with vessel [3 permits withdrawal .'.--.Atthe start of operations under any given set I of any liquid fr m th washn st p which is'not Iofspinning conditions, the proportion ofprecipidelivered to vessel 21 The withdrawn liquid may ...tant tosolvent required in the liquid from the be stored for lateruse as asetting bath.

washing step and the rate at which that liquid -When the spinning isconducted at room tem- ..must be delivered to the setting bath tomaintain 40" perature, as is preferred, or at temperaturesbegtheicomposition of thebath constant, can be delow 100 C., and thewashing liquid is heated, it ..termined byobservation of the-refractiveindex of is necessary to cool the liquid from h Washing Lathe bath;Thereafter, adjustments in the washstep-before delivering it to thebath. This may ing conditions and in the rate at which the wash beaccomplished by associating anysuit'able coolliquid is delivered to thebath .are generally not ins-means, for example, a cooling'coil ill, withwrequired so long as the spinning conditions are vessel 13 as shown,through which a cooling fiuid not changed; However, if such adjustmentsare is c r ul t d o a just the temp t e -1iequired,.they may be madesimply by increasing liquid collected in vessel I 3 to the temperatureCon-decreasingthe. rate of flow of the. washing of the-spinning bathbefore it enters vessel 2. .1i'quid tethe washing zone, and/or byincreasing 5O An' advantage of the present method is that theavoridecreasing the rate of fiow of the liquid from gtheewashing step tothe setting bath. Suitable F apparatus .for the production of artificialor syn- N. thetic fibers or. threads in accordance with: the inventionis illustrated. in the. accompanying spinning solvent is recoveredfrom-mixtures in which it is present in'relatively-high concentration i.e., from the settirig bath or from liquid remaining after initialwashing of the fibers or the like.

.,. drawing in which the single figure is a diagram- .e.matic,-.perspective view of a preferred embodi- ;.ment of the invention.

-.cReferring tothe drawing, the solution of the If the washing liquid isa mixture of the precipitant'and'solvent, the proportion of solventpresent therein must be controlled and should not be greater thanone-half the amount of solvent present in the setting bath.

If it is desired to stretch the'article for orientation,-the article maybe stretched prior to, during, or after the initial washing attemperatures desfibereforming. material is extruded through the 0,,.spinneretl into vessel2 containing a settingbath scomprisingthepredetermined. relative proporevtionsof solvent" and precipitant; .Thefibers are withdrawn from the bath under the guide 3 and ,lapped-aroundgodet 4, a thread displacing guide 5 .being ,supportedadjacentthe godet..From

godet 4; the fibers are passed upwardly through the. open'trough 6 andlapped around godet 1, a

Z""'threaddisplacing guide 8 beingsupportedadja- --pehding on thematerial shaped, and may or may not be given an" after-stretch. Forexample,

" freshly-formed'fibers' of the acrylonitrile poly- -mers o1" blends'maybe stretched'IOO to-300%-at temperatures up to' 100 stretched morethan300% 0., or they may be at temperatures above cent to that godet toassist in laying the fibers.

.' ;As shown, godets 4 and 1 are of the same size 100 0., and suchstretching may be the only stretch'given the-fibers. Or the fibers maybe and may be driven at different peripheral speeds stretched-up to' 200chi-300% attemperatures of i to stretch the fibers. If desired, godets 4and 1 "100 0;, "a after-stretched tt mperatures may betof.difier'ent'sizes and driven at the same above-100 0:; theafter-stretching beingper- "speed" to accomplish the stretching. As theformed either before or =after'final drying of the fibers. In {the'embodimentillustrated on the drawing-the acrylonitrile polymer fibersmay be I stretched between "the godets' 4 and 1 simultaneously withwashing thereof with water at any temperature up to 100 C., for instancea temperature between ordinary room temperature and 100 0., v and thenafter-stretched at temperatures above l-' C. If the acrylonitrilepolymer fibers are to be simultaneously stretched and heated to atemperature above 100 C., the godet used in-the production of shapedarticle's, espe- -cially fibers of the acrylonitrile polymers, whichterm is intended to include polyacrylonitrile, co-

polymers and interpolymers of a'crylonitrile with one or more othervinyl type monomers contain-. 1 ing at least 70% of acrylonitrile byweight in the polymer molecule, and blends comprising the acrylonitrilepolymers. Examplesof the latter are those compositions obtainedbyblending an acrylonitrile' polymer containing, by weight in themolecule at least 70% of acrylonitrile with a copolymer of from to 70%of acrylonitrile and from'30 to 90% of a'yinyl-substituted heterocyclictertiary amine, such as a vinylpyridine'to obtain a blend having anoverall content'of the poly:

merized vinyl-substituted tertiary heterocyclic amine of from 2 to 50%,based ontheweight of -.i th'eblend. I The following examples illustratea specific embodiment ofx'the invention:

Emamplel Using apparatus as shown in the drawing, a

' 3000 filament tow was formed by continuously extruding a spinningsolution comprising a homo: geneous mixture of N,N-dimethylacetamide and14.2% by weight of a polymer containing about 95% of acrylonitrile andabout 5% of 2-vinylpyridine throughaspinneret into a setting bath atroom temperature and consisting of 58% of N,N-dimethylacetamide and 42%of water, by weight, the solution being delivered through the spinneretat a rate of 1.76 lbs/minute. The tow of filaments carried 0.5 lb. ofN,N-dimethylacetamide per minute out of the setting bath into the trough6. Water at about 100 C. was delivered to the trough at a rate of agallon (8.33 lbs.) per minute. The liquid from the washing was collectedin vessel 13, in which it was cooled to room temperature. From vessel l3the liquid was continuously delivered to the bath in vessel 2 at a rateof 0.146 gallon (1.21 lbs.) per minute. Under these conditions, thecomposition of the setting bath remained at 58% of N,N-dimethylacetamideand 42% of water from the beginning to the end of the spinning whichwas, performed continuously over a period of eight hours.

Example II Using apparatus as shown in the drawing, a 5000 filament towwas formed by continuously extruding a spinning solution comprising a.homogeneous mixture of N,N-dimethylacetamide and 14.2% of a copolymer of95% acrylonitrile and 5% of 2-vinylpyridine, at room temperature andconsisting of 58% of N,N-dimethylacetamide and 42% of water, by weight,the solution being delivered through the spinneret at a rate of 2.937lbs. per minute. The tow of filaments carried 0.834 lb. ofN,N-dimethylacetamide per minute from the setting baths; into trough.6.- waterat about 100 C. was delivered to .the trough 1mm i vessel 9 ata rateroi one gallon'l(8.38 lbs.)rper minute. The water from the washingwhich consisted of water and 9.12% of N,N dimethylacetamide, wascollected'in vessel l3, in which it was cooledto room temperature by thecooling fluid circulatingin coil l8, and from which it was continuouslydelivered to the bath in vessel :2 at a rate of 0.26 gallon (2.17 lbs.)per minute. Under these conditions the composition of the setting bathwas maintained at 58% .of N;N-'- dimethylacetamide and 42% of waterthroughout :the spinning, which consumed eight hours.

- The apparatus and method illustrated are'particularly advantageousinthe" production of acrylonitrile polymer yarns whichare unique in that,as disclosed in the pending application of Howard M. Hoxie and Helen G.Sommar, Serial No. 83,374, filed, March 25, 1949, the amount of residualsolvent present in-the yarnsiscritical I for optimum stretch'and-impr'ovement in the tenacity at anygiventemperature from 100 C. upto the temperature at which the yarn is damaged. The yarn leaving thesetting" bath comprising the solvent and precipitant contains an amountof solvent' which appreciably greater than 1.5% by weight; andordinarily, prolonged washing would be requiredto-"reduce the solvent toless than 1.5%; However, in practicing this invention, theconditions,such as the length and width of trough 6. the angle ofinclination of the troughwith respect to ve'ssels 2 and 9, the rate offiow of the washing liquid through the trough countercurrentlytothe'yarn advancing from thebath, and the -temperature of the washingliquid may be selected so that the yarn leaving the trough after theinitial washing contains less than 1.5% of the-spir'ming'isolvent andadditional washings are not 'neces'sary prior to stretching the yarns attemperatures above 100 C.

Since certain changes may be made in carrying out the invention withoutdeparting from its spirit and scope, it is intended that all mattercontained in the foregoing description is to be interpreted asillustrative and not in a limiting sense. In the claims, the terms"solven and solution are intended to include true solvents and solutionsas well as dispersing agents and dispersions or colloidal solutions ormixtures in which the fiberor film-forming material is substantiallyuniformly dispersed. The term fibers is intended to include filamentsand yarns.

I claim:

1. A method of forming artificial and synthetic fibers and other shapedarticles which comprises continuously extruding a solution oi thematerial to be shaped into a setting bath comprising a mixture of thesolvent and a liquid precipitant for the material to be shaped, whichprecipitant is anextractive for the solvent, 0on

tinuously withdrawing the shaped article from the setting bath to theatmosphere, continuously washing the article as it advances from thesetting bath, and above the level of the setting bath, with a confinedstream of liquid flowing countercurrently to the direction of travel ofthe article "x joi the isolation-- of tha material to be -shaped;

11 so that ithe relative proportions of precipitant -r:and1-:so1vent in.;the setting:bath.v are: thereby .::.-:imaintainedsubstantiallyconstant fromizthe beginning torthegend or :the extrusion. 2, A method Jas in claim 1, wherein the article iis'istretched simultaneously withwashing thereof. 1 :3'.-A:method asin :claim 1', :wherein thematerial.tobe shaped comprises an acrylonitrile poly- :ernereontaimnggiby-weighiz mime-polymer mole- 'mcule -atnleast 70%-of'acrylonitrile.

1: '4; A method as in claim -1-,- wherein the-matei rial tcvbe-shaped isa :blend of an acrylonitrile ,-poly mer containing by :weight inthe:;:polymer :molecule,; at least"70% or vacr-ylonitrile with ai=eopolymer of from 10 to-'7.0% of acrylonitrile m -and from30 to 90%Qi'a:vinyl-substitutedheteroe cyclic tertiary amine.

5-. A method-fas in claim -1, -Whereini:the material to.- be; shaped isa-zblend of an acrylonitrile 1 polymercontainingiby-weight in thepolymer molecule, atleast 70%-:of-acrylonitrile andacoipolymer of-irom16 to 7.0% of acryloni-trileand -..:from 30 to 9.0% of avinylpyridine. lfi. :A-method as in'claim l wherein thefmatere -rial tobeshaped isacellulose zorganic acidester.

7i A-methodv-as in claim 1,: wherein-the mate- 1 rial to be:shaped issecondary cellulose acetate.

1; 8. Amethod-as in claim 1; wherein the material to be-shaped is .asynthetic-resin.

\ 9. -A method of forming synthetic fibers from a "fiberforming-composition comprising an acrylo- -ni'tri-le polymer containing,by weight in the polymu-molecule, at least 70% of'acrylonitrile, which:comprises =continuouslyextruding a solution of V :-the polymer indimethylacetamide into a setting batheomprisinga. mixture of water anddimethwylacetamide in a selected proportion between 20 1 :and 70 byvolume; eon-tinuouslyiwithdrawing the rfibers irom the bath to. theatmospherercontinua eously washingthe fibers advancing from thebath,

andabove the level of the bath, with a confined stream of: liquidconsisting ofwater and at-most a minor proportion ofdimethylacetamide-flowing countercurrently to the direction of travel ofthe fibers, collecting the liquid from the washing :step, andcontinuously:deliveringlliquidcollected from the-washing step to thesetting bath in a icontrolled amount which isdependent onthe relativeproportion of water to dimethylacetamide in the liquid from the washingstep and on the amount of -dimethylacetamide introduced 'into the'bath'by the solution of the polymer, so

that the relative proportions of-water and 'dimethiylacetamide in thesetting bathzare thereby maintained substantiallyconstant from thebeginning to the end of theextrusion.

10. A method as in claim 9, wherein the fibers advancing from thesetting bath are vwashed with water having a; temperature between roomtem- :perature and 100 0.

11. A method as in-claim 9, wherein the fibers are stretchedsimultaneously with washing thereof.

12. .A'method as in claim 9, wherein. thefibers advancing from thesetting bath are washed at a 1 temperature between room temperature and100 tertiary amine.

14; A method as in claim 9, wherein the materia1 to be shaped is a blendof. an acrylonitrile polymer containing, by'weight in the polymermoleculaat least 7.0% of acrylonitrile with a copolymer of from 10 toof-acrylonitrile-and i from 30 to of a vinylpyridine.

HOWARD- M. HOXLE.

M flNo-referencesloited.

1. A METHOD OF FORMING ARTIFICIAL AND SYNTHETIC FIBERS AND OTHER SHAPEDARTICLES WHICH COMPRISES CONTINUOUSLY EXTRUDING A SOLUTION OF THEMATERIAL TO BE SHAPED INTO A SETTING BATH COMPRISING A MIXTURE OF THESOLVENT AND A LIQUID PRECIPITANT FOR THE MATERIAL TO BE SHAPED, WHICHPRECIPITANT IS AN EXTRACTIVE FOR THE SOLVENT, COMTINUOUSLY WITHDRAWINGTHE SHAPED ARTICLE FROM THE SETTING BATH TO THE ATMOSPHERE, CONTINUOUSLYWASHING THE ARTICLE AS IT ADVANCES FROM THE SETTING BATH, AND ABOVE THELEVEL OF THE SETTING BATH, WITH A CONFINED STREAM OF LIQUID FLOWINGCOUNTERCURRENTLY TO THE DIRECTION OF TRAVEL OF THE ARTICLE ANDCONSISTING OF THE PRECIPITANT AND AT MOST A MINOR PROPORTION OF THEEXTRUSION SOLVENT, COLLECTING THE LIQUID FROM THE WASHING STEP, ANDCONTINUOUSLY DELIVERING LIQUID COLLECTED FROM THE WASHING STEP TO THESETTING BATH IN A CONTROLLED AMOUNT WHICH IS DEPENDENT ON THE RELATIVEPROPORTION OF PRECIPITANT TO SOLVENT IN THE LIQUID SOLVENT INTRODUCEDINTO THE BATH BY EXTRUSION OF THE SOLUTION OF THE MATERIAL TO BE SHAPED,SO THAT THE RELATIVE PROPORTIONS OF PRECIPITANT AND SOLVENT IN THESETTING BATH ARE THEREBY MAINTAINED SUBSTANTIALLY CONSTANT FROM THEBEGINNING TO THE END OF THE EXTRUSION.